Resolved and Fading Anomalies

• W Boson Mass: The crisis sparked by the 2022 CDF II measurement, which reported a mass 7σ higher than the Standard Model (SM) prediction, is considered resolved. In September 2024, the CMS experiment released a new, highly precise measurement (80,360.2±9.9 MeV) that aligns perfectly with the SM prediction (80,357±6 MeV) and results from ATLAS and LHCb. This suggests the CDF II result was likely an outlier due to unrecognized systematic errors.

• RK​ and RK∗​: Previous hints of Lepton Flavour Universality violation in b→sℓ+ℓ− decays (where muons appeared to be produced less frequently than electrons) have disappeared. Updated LHCb analyses using the full 9 fb−1 dataset show these ratios are consistent with the SM. The earlier discrepancies are now attributed t ...